Digital watermarking is a process for modifying physical or electronic media to embed a machine-readable code into the media. The media may be modified such that the embedded code is imperceptible or nearly imperceptible to the user, yet may be detected through an automated detection process. Most commonly, digital watermarking is applied to media signals such as images, audio signals, and video signals. However, it may also be applied to other types of media objects, including documents (e.g., through line, word or character shifting), software, multi-dimensional graphics models, and surface textures of objects.
Digital watermarking systems typically have two primary components: an encoder that embeds the watermark in a host media signal, and a decoder that detects and reads the embedded watermark from a signal suspected of containing a watermark (a suspect signal). The encoder embeds a watermark by subtly altering the host media signal. The reading component analyzes a suspect signal to detect whether a watermark is present. In applications where the watermark encodes information, the reader extracts this information from the detected watermark.
Several particular watermarking techniques have been developed. The reader is presumed to be familiar with the literature in this field. Particular techniques for embedding and detecting imperceptible watermarks in media signals are detailed in the assignee's co-pending application Ser. No. 09/503,881, now U.S. Pat. No. 6,614,914, and U.S. Pat. No. 6,122,403, which are hereby incorporated by reference.
U.S. Patent Application Publication 2003-0053654 discloses a form of marking of physical objects to convey location information for navigation of aircraft. Also, U.S. patent Publication 2002-0169962 describes a form of digital watermarking on physical objects to convey orientation and location information used in controlling robots. This disclosure incorporates these documents and describes embedding of information in objects that enables unmanned vehicles to identify the objects and determine their orientation and location relative to the objects for use in navigation.
The invention provides methods, systems, and related software for automated navigation. One aspect is a method for automated navigation. The method captures an image scan of a digital watermark on an object. It extracts orientation and location information of an image sensor relative to the object from the digital watermark. It performs object identification based on auxiliary information carried in the digital watermark. Finally, it uses the orientation, location and object identification information to control movement of a vehicle.
Further features will become apparent with reference to the following detailed description and accompanying drawings.